Originally Posted by blueplume
I'm looking for a link to sensible explanations about how TCAS really works (I understand mode A/mode C basics) but want to know more about how transponders talk to each other.
ACAS / ACAS II are specified in ICAO Annex 10 Chapter 4. I don't know if the algorithms of TCAS 6 or 7 (Implementations of ACAS) were published. If they can be found anywhere, I would be very interested too.